<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			body {
				perspective: 500px;
			}

			.a {
				position: relative;
				width: 100px;
				height: 100px;
				background-color: skyblue;
				margin: 50px auto;
				font-size: 12px;
				font-weight: 700;
				color: #fff;
				text-align: center;
				line-height: 100px;
				border-radius: 50%;
				transition: all .5s;
				transform-style:preserve-3D
			}

			.b {
				/* display: none; */
				position: absolute;
				top: 0;
				left: 0;
				width: 100px;
				height: 100px;
				background-color: hotpink;
				border-radius: 50%;
				transition: all .5s;
				
				/* 先让其中的一个盒子翻转180度实现背靠背的效果 */
				transform: rotateY(180deg);

			}

			.a:hover {
				transform: rotateY(180deg);
			}
		</style>
	</head>
	<body>
		<!-- 正常做法应该在父级a里面放两个盒子 -->
		<div class="a">
			让我看看!
			<div class="b">哟，你脸红啦!</div>
		</div>
	</body>
</html>
